Isotoma fluviatilis
A low, mat-forming perennial ground cover that hugs the ground at one to three inches tall and spreads steadily by creeping stems to form a dense green carpet. It takes full sun to part shade and prefers consistent, regular water, thriving in mild coastal and inland conditions. From spring into summer it is studded with tiny star-shaped pale blue flowers, making it a favorite lawn substitute and filler between stepping stones and pavers, along borders and pathways, and in any spot where a soft, walkable mat is wanted.